Somatostatin or somatotropin release-inhibiting factor is an antagonist of growth hormone releasing factor (GHRF) and is believed to interfere with growth by inhibiting growth hormone (GH) secretion.
Scientists have theorized that if somatostatin (S) does inhibit growth hormone secretion, manipulation of its levels may affect growth rate and body composition of animals bred for meat production. Literature reports of efforts to accomplish animal weight gain by auto-immunization, however, have been inconsistent. For example, Spencer and Williams reported auto-immunizing lambs with somatostatin linked to a carrier protein. The auto-immunized lambs gained weight more rapidly than did the control lambs; averaging 135% of the weight of the control lambs after nine weeks of treatment. Plasma somatomedin levels showed a five fold increase over the control levels; however, neither growth hormone levels nor insulin levels increased (Animal Production 32:376 (1981); Veterinary Record, p. 484, (May 22, 1984). In similar tests, Varner et al. reported that baseline and overall serum growth hormone concentrations were higher in anti-somatostatin (anti-S) auto-immunized lambs than in controls (Endocrinology 106:1027 (1980)). Despite this, Varner found that the immunized lambs gained significantly less weight than did control animals.
Thus, literature results on weight gain through active immunization are discrepant. It therefore is an object of this invention to develop a reproducible method for enhancing animal growth rates.